Various blood processing systems now make it possible to collect particular blood components, rather than whole blood, from a blood source. Typically, in such systems, whole blood is drawn from a blood source, such as a human donor, the particular blood component is separated, removed, and collected, and the remaining blood components are returned to the blood source. Removing only particular components is advantageous when the blood source is a human donor or patient, because potentially less time is needed for the donor's body to return to pre-donation levels, and donations can be made at more frequent intervals than when whole blood is collected. This increases the overall supply of blood components, such as plasma and platelets that are available for transfusion and/or therapeutic treatment.
Platelets are collected from healthy donors and administered to patients whose ability to produce platelets has been compromised by chemotherapy of other conditions. In order to collect platelets, whole blood is first separated into its constituent components, including platelets, most typically by centrifugation. Centrifugal separators are well known and allow the platelets to be collected while returning other components, e.g., red blood cells, plasma, back to the donor in a process known as “apheresis.” An example of an automated apheresis device is the AMICUS® separator sold by Fenwal, Inc. of Lake Zurich, Ill., which is an affiliate of Fresenius Kabi AG of Bad Homburg, Germany, and which is described in greater detail in U.S. Pat. No. 5,868,696 and International Application Publication WO2013/048984, both of which are incorporated herein by reference.
Using an automated apheresis device, the whole blood is obtained from a source such as a healthy human donor by accessing the vascular system of the donor with a phlebotomy or venipuncture needle. As will be described in greater detail below, the hollow needle is in flow communication with a disposable tubing and container fluid circuit or kit that is configured for use with the apheresis device. Prior to venipuncture, the donor's skin is typically cleaned or otherwise prepared to remove bacteria that may reside on the surface of the donor's skin. Notwithstanding recent improvements in skin preparation, some residual bacteria may remain on the skin. For example, the so-called “skin plug,” (the piece of skin that is dislodged by the puncturing action of the needle) may be carried into the blood and potentially introduce bacteria into the blood being withdrawn from the donor. In addition, bacteria present on the surface of the donor's skin may be carried into the blood independent of a dislodged skin plug. Eventually, the bacteria associated can find its way into the collected blood product, i.e., platelets.
In an effort to diminish the potential risk of bacterial contamination of the whole blood and more particularly, the collected component derived from the whole blood, “sample diversion” systems have been developed which divert the initial flow of blood to a satellite pouch of limited volume. This sample pouch serves the dual purpose of (a) providing a small volume of the donor's whole blood which can be used for testing and analysis and (b) diverting the initial flow of blood which is likely to contain the skin plug or bacteria away from the separation and collection containers and the flow paths leading thereto. Such sample diversion systems are described in U.S. Pat. Nos. 7,044,941, 6,520,948, 6,387,086 and 8,517,970, all of which are incorporated herein by reference.
While the sample diversion systems described in the above-identified patents have been very effective in reducing the possibility of bacterial contamination of collected blood platelets, there is still a moderate risk that bacteria residing on the skin of the patient may not be diverted to the sample pouch with the initial volume of whole blood, and instead be carried over to the separation chambers and collection containers of the disposable fluid circuit. One way to ensure greater confidence that the skin plug and any associated bacteria are diverted to the sample pouch would be to increase the volume of the initial flow of blood that is collected in the sample pouch. However, doing so would increase the blood loss in the donor as the whole blood collected in the sample pouch is not processed and is, in effect, “waste.”
Thus, it would be desirable to provide a method and system that further decreases the risk of bacterial contamination in collected platelets without increasing blood loss in the donor and without adding substantial time to the platelet collection procedure. The methods and systems described herein address this need.